drivers/platform/x86/siemens/simatic-ipc-batt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Siemens SIMATIC IPC driver for CMOS battery monitoring
   4  *
   5  * Copyright (c) Siemens AG, 2023
   6  *
   7  * Authors:
   8  *  Gerd Haeussler <gerd.haeussler.ext@siemens.com>
   9  *  Henning Schild <henning.schild@siemens.com>
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/delay.h>
  15 #include <linux/io.h>
  16 #include <linux/ioport.h>
  17 #include <linux/gpio/machine.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/hwmon.h>
  20 #include <linux/hwmon-sysfs.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/platform_data/x86/simatic-ipc-base.h>
  26 #include <linux/sizes.h>
  27
  28 #include "simatic-ipc-batt.h"
  29
  30 #define BATT_DELAY_MS   (1000 * 60 * 60 * 24)   /* 24 h delay */
  31
  32 #define SIMATIC_IPC_BATT_LEVEL_FULL     3000
  33 #define SIMATIC_IPC_BATT_LEVEL_CRIT     2750
  34 #define SIMATIC_IPC_BATT_LEVEL_EMPTY       0
  35
  36 static struct simatic_ipc_batt {
  37         u8 devmode;
  38         long current_state;
  39         struct gpio_desc *gpios[3];
  40         unsigned long last_updated_jiffies;
  41 } priv;
  42
  43 static long simatic_ipc_batt_read_gpio(void)
  44 {
  45         long r = SIMATIC_IPC_BATT_LEVEL_FULL;
  46
  47         if (priv.gpios[2]) {
  48                 gpiod_set_value(priv.gpios[2], 1);
  49                 msleep(150);
  50         }
  51
  52         if (gpiod_get_value_cansleep(priv.gpios[0]))
  53                 r = SIMATIC_IPC_BATT_LEVEL_EMPTY;
  54         else if (gpiod_get_value_cansleep(priv.gpios[1]))
  55                 r = SIMATIC_IPC_BATT_LEVEL_CRIT;
  56
  57         if (priv.gpios[2])
  58                 gpiod_set_value(priv.gpios[2], 0);
  59
  60         return r;
  61 }
  62
  63 #define SIMATIC_IPC_BATT_PORT_BASE      0x404D
  64 static struct resource simatic_ipc_batt_io_res =
  65         DEFINE_RES_IO_NAMED(SIMATIC_IPC_BATT_PORT_BASE, SZ_1, KBUILD_MODNAME);
  66
  67 static long simatic_ipc_batt_read_io(struct device *dev)
  68 {
  69         long r = SIMATIC_IPC_BATT_LEVEL_FULL;
  70         struct resource *res = &simatic_ipc_batt_io_res;
  71         u8 val;
  72
  73         if (!request_muxed_region(res->start, resource_size(res), res->name)) {
  74                 dev_err(dev, "Unable to register IO resource at %pR\n", res);
  75                 return -EBUSY;
  76         }
  77
  78         val = inb(SIMATIC_IPC_BATT_PORT_BASE);
  79         release_region(simatic_ipc_batt_io_res.start, resource_size(&simatic_ipc_batt_io_res));
  80
  81         if (val & (1 << 7))
  82                 r = SIMATIC_IPC_BATT_LEVEL_EMPTY;
  83         else if (val & (1 << 6))
  84                 r = SIMATIC_IPC_BATT_LEVEL_CRIT;
  85
  86         return r;
  87 }
  88
  89 static long simatic_ipc_batt_read_value(struct device *dev)
  90 {
  91         unsigned long next_update;
  92
  93         next_update = priv.last_updated_jiffies + msecs_to_jiffies(BATT_DELAY_MS);
  94         if (time_after(jiffies, next_update) || !priv.last_updated_jiffies) {
  95                 if (priv.devmode == SIMATIC_IPC_DEVICE_227E)
  96                         priv.current_state = simatic_ipc_batt_read_io(dev);
  97                 else
  98                         priv.current_state = simatic_ipc_batt_read_gpio();
  99
 100                 priv.last_updated_jiffies = jiffies;
 101                 if (priv.current_state < SIMATIC_IPC_BATT_LEVEL_FULL)
 102                         dev_warn(dev, "CMOS battery needs to be replaced.\n");
 103         }
 104
 105         return priv.current_state;
 106 }
 107
 108 static int simatic_ipc_batt_read(struct device *dev, enum hwmon_sensor_types type,
 109                                  u32 attr, int channel, long *val)
 110 {
 111         switch (attr) {
 112         case hwmon_in_input:
 113                 *val = simatic_ipc_batt_read_value(dev);
 114                 break;
 115         case hwmon_in_lcrit:
 116                 *val = SIMATIC_IPC_BATT_LEVEL_CRIT;
 117                 break;
 118         default:
 119                 return -EOPNOTSUPP;
 120         }
 121
 122         return 0;
 123 }
 124
 125 static umode_t simatic_ipc_batt_is_visible(const void *data, enum hwmon_sensor_types type,
 126                                            u32 attr, int channel)
 127 {
 128         if (attr == hwmon_in_input || attr == hwmon_in_lcrit)
 129                 return 0444;
 130
 131         return 0;
 132 }
 133
 134 static const struct hwmon_ops simatic_ipc_batt_ops = {
 135         .is_visible = simatic_ipc_batt_is_visible,
 136         .read = simatic_ipc_batt_read,
 137 };
 138
 139 static const struct hwmon_channel_info *simatic_ipc_batt_info[] = {
 140         HWMON_CHANNEL_INFO(in, HWMON_I_INPUT | HWMON_I_LCRIT),
 141         NULL
 142 };
 143
 144 static const struct hwmon_chip_info simatic_ipc_batt_chip_info = {
 145         .ops = &simatic_ipc_batt_ops,
 146         .info = simatic_ipc_batt_info,
 147 };
 148
 149 int simatic_ipc_batt_remove(struct platform_device *pdev, struct gpiod_lookup_table *table)
 150 {
 151         gpiod_remove_lookup_table(table);
 152         return 0;
 153 }
 154 EXPORT_SYMBOL_GPL(simatic_ipc_batt_remove);
 155
 156 int simatic_ipc_batt_probe(struct platform_device *pdev, struct gpiod_lookup_table *table)
 157 {
 158         struct simatic_ipc_platform *plat;
 159         struct device *dev = &pdev->dev;
 160         struct device *hwmon_dev;
 161         unsigned long flags;
 162         int err;
 163
 164         plat = pdev->dev.platform_data;
 165         priv.devmode = plat->devmode;
 166
 167         switch (priv.devmode) {
 168         case SIMATIC_IPC_DEVICE_127E:
 169         case SIMATIC_IPC_DEVICE_227G:
 170         case SIMATIC_IPC_DEVICE_BX_39A:
 171         case SIMATIC_IPC_DEVICE_BX_21A:
 172         case SIMATIC_IPC_DEVICE_BX_59A:
 173                 table->dev_id = dev_name(dev);
 174                 gpiod_add_lookup_table(table);
 175                 break;
 176         case SIMATIC_IPC_DEVICE_227E:
 177                 goto nogpio;
 178         default:
 179                 return -ENODEV;
 180         }
 181
 182         priv.gpios[0] = devm_gpiod_get_index(dev, "CMOSBattery empty", 0, GPIOD_IN);
 183         if (IS_ERR(priv.gpios[0])) {
 184                 err = PTR_ERR(priv.gpios[0]);
 185                 priv.gpios[0] = NULL;
 186                 goto out;
 187         }
 188         priv.gpios[1] = devm_gpiod_get_index(dev, "CMOSBattery low", 1, GPIOD_IN);
 189         if (IS_ERR(priv.gpios[1])) {
 190                 err = PTR_ERR(priv.gpios[1]);
 191                 priv.gpios[1] = NULL;
 192                 goto out;
 193         }
 194
 195         if (table->table[2].key) {
 196                 flags = GPIOD_OUT_HIGH;
 197                 if (priv.devmode == SIMATIC_IPC_DEVICE_BX_21A ||
 198                     priv.devmode == SIMATIC_IPC_DEVICE_BX_59A)
 199                         flags = GPIOD_OUT_LOW;
 200                 priv.gpios[2] = devm_gpiod_get_index(dev, "CMOSBattery meter", 2, flags);
 201                 if (IS_ERR(priv.gpios[2])) {
 202                         err = PTR_ERR(priv.gpios[2]);
 203                         priv.gpios[2] = NULL;
 204                         goto out;
 205                 }
 206         } else {
 207                 priv.gpios[2] = NULL;
 208         }
 209
 210 nogpio:
 211         hwmon_dev = devm_hwmon_device_register_with_info(dev, KBUILD_MODNAME,
 212                                                          &priv,
 213                                                          &simatic_ipc_batt_chip_info,
 214                                                          NULL);
 215         if (IS_ERR(hwmon_dev)) {
 216                 err = PTR_ERR(hwmon_dev);
 217                 goto out;
 218         }
 219
 220         /* warn about aging battery even if userspace never reads hwmon */
 221         simatic_ipc_batt_read_value(dev);
 222
 223         return 0;
 224 out:
 225         simatic_ipc_batt_remove(pdev, table);
 226
 227         return err;
 228 }
 229 EXPORT_SYMBOL_GPL(simatic_ipc_batt_probe);
 230
 231 static int simatic_ipc_batt_io_remove(struct platform_device *pdev)
 232 {
 233         return simatic_ipc_batt_remove(pdev, NULL);
 234 }
 235
 236 static int simatic_ipc_batt_io_probe(struct platform_device *pdev)
 237 {
 238         return simatic_ipc_batt_probe(pdev, NULL);
 239 }
 240
 241 static struct platform_driver simatic_ipc_batt_driver = {
 242         .probe = simatic_ipc_batt_io_probe,
 243         .remove = simatic_ipc_batt_io_remove,
 244         .driver = {
 245                 .name = KBUILD_MODNAME,
 246         },
 247 };
 248
 249 module_platform_driver(simatic_ipc_batt_driver);
 250
 251 MODULE_LICENSE("GPL");
 252 MODULE_ALIAS("platform:" KBUILD_MODNAME);
 253 MODULE_AUTHOR("Henning Schild <henning.schild@siemens.com>");